A lot of people think full-stack just means React + Node.js. But a true full-stack engineer needs to understand what happens after the code leaves localhost. If you can build a beautiful UI and write an API, but have no idea how databases scale, how caching works, or how to debug a deployment pipeline, you’re missing a massive piece of the stack. DevOps and infrastructure knowledge are what separate a full-stack coder from a full-stack engineer.